Portable electronic devices and wearable electronic devices are under active development. For example, a thin portable electronic book is disclosed in Patent Document 1.
Portable electronic devices and wearable electronic devices operate using batteries as power sources. Portable electronic devices need to withstand extended use and thus can incorporate high-capacity secondary batteries. In that case, there occurs a problem that the size and weight of the electronic devices are large. In view of this problem, a small and thin high-capacity secondary battery that can be incorporated in a portable electronic device is under development.
Metal cans are used as exterior bodies of secondary batteries, and electrolytes and the like are contained in the metal cans.